<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <p>{{ total }}</p>
        <button-counter v-on:increment="incrementTotal"></button-counter>
        <button-counter v-on:increment="incrementTotal"></button-counter>
    </div>
    <script src="../js/vue.js" charset="utf-8"></script>
    <script type="text/javascript">
        //props down, events up

        Vue.component('button-counter', {
            template: '<button @click="increment">{{ counter }}</button>',
            data: function () {
                return {
                    counter: 0
                }
            },
            methods: {
                increment: function () {
                    this.counter += 1
                    this.$emit('increment')
                }
            }
        })

        new Vue({
            el: '#app',
            data: {
                total: 0
            },
            methods: {
                incrementTotal: function () {
                    this.total += 1
                }
            }
        })

    </script>
</body>
</html>
